1. Field of the Invention
The present invention relates to a compact wide-angle lens system, and more particularly to a wide-angle lens system that offers a total angle of view of about 150 degrees and that is suitable for use with a solid-state image sensor in a digital input device (such as a digital still camera or a digital video camera) like a videophone, an intercom, a surveillance camera, a vehicle-mounted camera, or the like.
2. Description of Related Art
There have conventionally been proposed many wide-angle lens systems designed as an image-taking optical system for use with a solid-state image sensor in a surveillance camera, a vehicle-mounted camera, or the like. Among such wide-angle lens systems are those that offer a total angle of view of about 150 degrees, of which some are composed of, for example, eight lens elements (see Patent Publication 1 listed below).
Patent Publication 1: JP-A-2004-102162
The wide-angle lens system disclosed in Patent Publication 1 mentioned above, however, requires an extremely large number of lens elements, namely eight, and has a complicated construction with an extremely large total length. Moreover, all the lens elements are glass lens elements, making the wide-angle lens system unsatisfactory in terms of cost and weight.